Young children with autism may demonstrate severe language impairment including the absence of vocal speech. This may limit the ability to mand (i.e., request) for preferred items or events and can lead to the development of problematic behavior that functions as a mand. The purposes of the present investigations were to (a) identify the function of gestures emitted by young children with autism, (b) examine differences in outcomes of mand training when the function of gestural behavior was either incorporated or not incorporated into mand training procedures, and (c) examine collateral effects of the mand training conditions on related but nontargeted behaviors.In Experiment 1, gestural behavior emitted by 5 nonvocal children with autism was functionally analyzed using a single subject alternating treatment design. Repeated applications of test and control conditions revealed gestures functioned as mands for attention for 1 participant and as mands for assistance obtaining a preferred item or event for 4 participants. Experiment 2 examined the effects of a video modeling (VM) intervention on acquisition of vocal or picture exchange mands under 2 experimental conditions. Function-based VM targeted response forms that were functionally equivalent to the gestures examined during Experiment 1 whereas nonfunction-based VM targeted response forms that were not related to participants' gestural mands. Differential effects of the VM conditions were examined using an alternating treatment within multiple probe across behaviors design.Participants acquired, generalized, and maintained mands taught during function-based VM but not during nonfunction-based VM. Additionally, the function-based condition resulted in clear improvements to problem behaviors and slight improvements to listener behaviors when compared to the nonfunction-based condition. Results are discussed in terms of the empirical and applied implications for function-based interventions and VM.
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